Naphthalic imidazole grease



United Sttes 3,102,860 NAPHTHALIC IMIDAZOLE GREASE Jacques L. Zakin, Hewlett, N.Y., assignor to Socony Mobil Oil Company, Inc, a corporation of New York No Drawing. Filed Aug. 31, 1960, Ser. No. 53,042 11 Claims. (Cl. 252-28) This invention has to do with new grease compositions, particularly grease compositions characterized by a high order of effectiveness throughout a Wide range of severe operating conditions.

For many years, there have been developments of improved greases designed to meet ever-increasing demands for effective lubrication of machinery. However with considerable progress being made in aircraft, missiles, rockets and advanced space craft, a need has arisen for greases resistant to high temperature operating conditions. Required are greases capable of functioning at temperatures in excess of 600 F.

It is an object of this invention, therefore, to provide greases capable of withstanding severe operating conditions. It is also an object to provide greases effective for high temperature use, such as 600 F. and higher. Other objects will be apparent fromthe following description.

This invention is predicated upon the discovery that greases of excellent character can be prepared from an oil of luubricating viscosity and a naphthalic imidazole.

The gelling agents of this invention are naphthalic imidazole compounds represented by the general formulae:

wherein R, R and R' can be the same or different atoms or groups. R, R" and R' can be: hydrogen; alkyl such as methyl, ethyl, propyl, etc.; alkoxy such as methoxy, ethoxy, propoxy, etc.; halogen such as chlorine, bromine, etc. Represented by x, y and z are zero and small whole numbers from 1 to 3.

Typical of such compounds are:

(trans form) 2) 0 t t N/ \N o -o (cis form) 3,102,860 Patented Sept. 3, 1963 (8) 0 Cl N\C (HJ -N N -o1 G- 3 01- N N CI 11.0.0 N C L N/ \N O C 2115 c") Nr 0 o t t H5CaO N/ \N 0 C2115 Particularly preferred herein is Vat Orange 7, shown above as compound (1). This is avail-able as Vat Brilliant Orange GR, a product of Harmon Colors, National Aniline Division of Allied Chemical Corporation. This is a fine powder, having a specific gravity of 1.5 8, a bulking value of 13.16 pounds per gallon and an oil absorption of 45 (in a slightly bodied oil).

Methods for the preparation of the foregoing compounds are available. A mixture of (3) and (4) can be formed by heating a mixture of o-phenylenediamine and 1,4,5,8-naphthalene tetracarboxylic acid in glacial acetic acid or in pyridine solution. Methods of preparation are described in US. Patents Nos. 1,588,451, 1,888,624 through 1,888,626 and 1,927,928. Compound (1) can be prepared by heating a mixture of (3) and (4) with ethyl alcohol and caustic potash, filtering the addition product so formed and bydrolyzing with water. Compound (1) can also be prepared by treating a mixture of (3) and (4) with sulfuric acid. Compound (2) can be prepared by treating a mixture of (3) and (4) with aluminum chloride and fractionally crystallizing the resulting product. Compound (4) is [formed by condensing 1,4,S,8-naphthalene tetracar-boxylic acid with 4-chloro-o-phenylene diamine in glacial acetic acid or in pyridine. A mixture of (5) and (6) is formed by condensing 1,4,5,8-naphthalene tetracarboxylic acid with 4-eth-oxy-o-phenylene diamine. Reference is made to the aforementioned patents for details in the preparation of compounds of this invention.

While it is preferred that the compounds of this invention can be used in substantially pure form (toner), it is to be understood that they can be used in the form of reduced toners. In the latter form, they are associated with an inert inorganic material such as an alumina hydrate, barium sulfate, clay, etc. When such inert inorganic materials are present, they are in amounts up to about percent by weight, preferably less than about 50 percent by weight.

It is to be understood also that more than one of the compounds contemplated herein can be used together in a grease composition.

The compounds of this invention are stable at high temperature, up to about 650 F. and beyond, and are well adapted for use in grease compositions formulated for high temperature operations. In this connection, they G1 I] HaC-C C-CH:

Oils used in the greases of this invention can be mineral or synthetic oils of lubricating viscosity. When high temperature stability 'is not a requirement of the finished grease, mineral lubricating oils can be used. Suitable mineral oils have a viscosity (S.U.V.) of at least 40 seconds at 100 F., and particularly those within the range of about 60 seconds to about 6000 seconds at 100 F.

Synthetic vehicles can be used, instead of mineral oils, or in combination therewith. Typical synthetic vehicles are: polypropylene, polypropylene glycol, trimethylol propane esters, neopentyl and pentaerythritol esters, (ii-(2- ethyl hexyl) sebacate, di-(Z-ethyl hexyl) adipate, dibutyl phthalate, polyethylene glycol di(2-ethyl hexoate), fluorocarbons, silicate esters, silanes, esters of phosphorus-containing acids, liquid ureas, ferrocene derivatives, hydrou or 0 genated mineral oils, chain type polyphenyls, siloxanes and silicones (polysiloxanes), alkyl-substituted diphenyl ethers typified by a butyl-substituted bis-(pphen-o-xy phenyl) ether, phenoxy phenyl ethers, etc.

Particularly preferred, herein, are polysiloxanes and mbis (m-phenoxyphen-oxy) benzene.

In the grease compositions contemplated herein, the naphthalic imidazole gelling agents are used in quantities from about 5 to about 50 percent by weight, and preferably from about 15 to about 30 percent by weight. The vehicles described above constitute the balance of the compositions except for relatively small quantities of the following characterizing materials which may be present.

It is to be understood, however, that the compositions contemplated herein can also contain other characterizing materials. For examples, antioxidants, corrosion inhibitors, viscosity index agents, fillers, etc, can be used. Among such materials are colloidal silica, calcium acetate, calcium carbonate and molybdenum disulfide. These characterizing materials do not detract from the lubricating value of the compositions of this invention, nor do they detract from the beneficial character of the naphthalic imidazole compounds; rather, these characterizing materials serve to impart their customary properties to the particular compositions in which they are incorporated.

The greases of this invention are prepared by dispersing a naphthalic imidazo-le compound in the vehicle. This may be accomplished by any mixing technique wherein solid particles are Wetted by a fluid. One advantageous method involves wetting of the naphthalic imidazole compound With a volatile liquid such as methyl alcohol and then adding the vehicle. The materials are milled together and warmed in order to remove the alcohol. A homogeneous product is obtained. Typical equipment for such use includes a colloid mill, 3-roll ink mill, Manton- Gaulin homogenizer and the like. Other advantageous techniques are the spray or jetting techniques described in applications of E. L. Armstrong et al., Serial Nos. 682,461, now Patent No. 2,950,248, and 683,815, now Patent No. 2,950,249, filed September 6 and 13, 1957, respectively.

A typical illustrative grease composition of this invention was prepared by dispersing twenty percent by Weight of compound (1)-Vat Orange 7in a particular siloX- ane. The latter is a polymethyl phenyl siloxane having a viscosity of 117 centistokes at 100 F. (Dow Corning Fluid 710). Compound (1) was wetted with methyl alco- 1101 and the siloxane was added thereto. The materials were milled with a spatula on a glass plate until roughly homogeneous, and were warmed to drive off the alcohol. The dispersion was then milled on a Hoover-Muller apparatus for four cycles each of 100 revolutions, with redistribution of the grease following each cycle.

Thickening power of a naphthalic imidazole, (1) above, was determined by measuring the flow properties of the grease described above. The fiow properties were measured on a Ferranti plate-and-cone viscometer. An apparent viscosity at 1000 see? and 100 F. was taken for comparison. The grease has a value of 11.9 poises as opposed to a value of 2.98 for the siloxane alone.

The results revealthat the naphthalic imidazole thicken the vehicle to a greater extent than would be predicted from a crude application of the Guth-Simha modification of the Einstein equation:

zviscosity of base fiuid (vehicle) =volume fraction of the naphtha-lie imidazole For example, compound 1) has a density of 1.58 and the siloxane a density of 1.07. Thus, a value of 4.4 poises would be predicted:

Instead of a value of 4.4, the actual value is a rather surprising 11.9.

That the naphthalic imidazoles of this invention have the desired thermal stability for high temperature greases is revealed by results obtained with compound (1). The compound was dried in an oven at 220 F., 65 hours at 450 F., 20 hours at 550 F., and finally heated for 20 hours at 650 F. The compound was in the form of a fine powder when placed in an open glass beaker, when the latter was placed in the oven. At the end of the test, there was a loss in weight of 11 percent and the compound was powdery in texture.

In contrast to the results obtained with compound 1), each of the compounds identified above as compounds (7) through (13) decomposed at or below 650 F.

As indicated above, the new lubricants can be used for a wide range of industrial applications. Typical applications are for lubrication of the machinery, mechanisms and vehicles mentioned above. In addition, greases constituted of the thickeners contemplated herein and of a vehicle resistant to radiation (such as a phenoxy phenyl ether), can be used for lubrication of equipment exposed to atomic radiation harmful to lubricants.

Although the present invention has been described with preferred embodiments, it is to be understood that modifications and variations may be resorted to, without departing from the spirit and scope of this invention, as those skilled in the art will readily understand. Such variations and modifications are considered to be within the purview and scope of the appended claims.

lubricating viscosity and from about 5 to about 50 percent by weight of the grease of a naphthalic imidazole represented by the general formulae:

C CL...

wherein R, and R" and R' are selected from the group consisting of hydrogen, alkyl, alkoxy and halogen, and x, y and z are selected from the group consisting of zero and small Whole numbers from 1 to 3.

2. A grease defined by claim 1 wherein the oil is a mineral oil.

3. A grease defined by claim 1 wherein the oil is a polysiloxane.

4. A grease defined by claim 1 wherein the oil is a phenoxyphenyl ether.

5. A grease defined by claim 1 wherein the naphthalic imidazole is Vat Orange 7.

6. A grease defined by claim 1 wherein the naphthalic imidazo'le is present in an amount between about 15 and about 30 percent by weight or" the grease.

7. A grease defined by claim 1 wherein there is also present up to about 10 percent by weight of the grease, of a colloidal silica.

8. A grease capable of functioning at temperatures as .high as about 600 F. consisting essentially of a polymethylphenyl siloxane and from about 5 to about 50 percent by weight of the grease of Vat Orange 7;

9. A grease capable of functioning at temperatures as high as about 600 F. consisting essentially of a polymethylphenyl siloxane, from about 15 to about 30 percent by weight of the grease of Vat Orange 7 and up to about 10 percent by weight of the grease of a colloidal silica.

10. A grease capable of functioning at temperatures as high as about 600 F. consisting essentially of m bis-(mphenoxy-phenoxy) benzene and from about 5 to about 50 percent by weight of the grease of Vat Orange 7.

11. A grease capable of functioning at temperatures as high as about 600 F. consisting essentially of m-bis-(mphenoxy-phenoxy) benzene, from about 15 to about '30 percent by weight of the grease of Vat Orange 7 and up to about 10 percent by weight of the grease of a colloidal silica.

References Cited in the file of this patent UNITED STATES PATENTS 2,679,480 Brannen et a1 May 25, 1954 2,848,417 Armstrong et a1. Aug. 19, 1958 2,851,418 Lyons et a1 Sept. 9, 1958 2,880,176 Roach et a1 Mar. 31, 1959 2,880,177 Lyons etal Mar. 31, 1959 2,908,644 Odell et al. Oct. 13, 1959 2,915,470 Armstrong et al Dec. 1, 1959 

1. A GREASE CAPABLE OF FUNCTIONING AT TEMPERATURES AS HIGH AS ABOUT 600*F. CONSISTING ESSENTIALLY OF AN OIL OF LUBRICATING VISCOSITY AND FROM ABOUT 5 TO ABOUT 50 PERCENT BY WEIGHT OF THE GREASE OF A NAPHTHALIC IMIDAZOLE REPRESENTED BY THE GENERAL FORMULA:
 7. A GREASE DEFINED BY CLAIM 1 WHEREIN THERE IS ALSO PRESENT UP TO ABOUT 10 PERCENT BY WEIGHT OF THE GREASE, OF A COLLOIDAL SILICA. 